This invention relates generally to transmission line and, more particularly, to an electrical grounding lug which grounds the transmission line.
Many transmission lines are subject to power surges from high energy conditions such as lightening strikes. The likelihood of being struck by lightening is increased if the transmission line is coupled to a device located on highly elevated structures, for example, an antenna on a tower. Grounding the transmission line is required to protect both the line and the base station equipment from these power surges related to lightening strikes.
Grounding may be accomplished by maintaining electrical contact between a grounding line and the outer conductor of the cable. This may be done by simply removing a portion of the outer cover of the cable to expose the outer conductor and making a contact. Most transmission lines, however, are used in places where such an open connection is not practical. The exposed section of the transmission line must be protected from the environment. Without adequate protection, the exposed area is subject to corrosion and eventual failure.
It is also desired that a high contact pressure be maintained between the conductor and the grounding line, since the grounding line is designed to handle high current conditions. Furthermore, in the case of a lightening strike, the magnetic forces of the bolt of lightening tend to cause the grounding line and conductor to repel from one another. The high contact pressure is also often difficult to maintain due to the variability of sizes of transmission lines, requiring that special clamps and/or contacts be made depending on the size of the transmission line.
To seal the exposed conductor after the grounding line is attached, tape is often used. Multiple tapes are needed in many cases so that the conductor is sealed from a variety of environmental issues. Using multiple tapes creates a burden on the installer both in the number of items that must be brought to every installation and in the time it takes to completely finish the installation. In addition, when the installer is forced to work in unfavorable conditions, such as sleet or rain, the integrity of the taping process may be compromised.
In systems which do not use tape, a clamp must be forced onto the conductor and the grounding line at the contact point. To effectively place the clamp, however, the installer must use great force. In adverse weather conditions, such as rain, the clamp may become slippery, making it difficult to use.
These systems also require the use of a separate housing to protect the exposed transmission line from the environment. Not only may the housing be cumbersome, placing the ground line and the transmission line in the housing adds an additional step for the installer, who may be working in adverse environments, such as snow or rain. The installer working under such conditions may also do a less thorough job in an effort to get out of the bad weather.
Another problem with many systems is the number of tools that need to be used for installation. A high number of tools increases the burden on the installer in terms of what must be carried and in time of installation.
Therefore, a need exists for a durable grounding device for grounding transmission lines which is capable of providing high contact pressure between the grounding line and transmission lines of a variety of sizes. A need also exists for a grounding device which is easy to assemble in adverse environments. Furthermore, a need exists for a sealing device which provides a reliable seal over the exposed section of the cable.
A device for grounding a transmission line having a diameter and an outer portion partially removed, revealing an exposed section, comprises an insert which is connected to the exposed section of the transmission line. A contact mechanism is included in the insert and provides an electrical contact with the exposed section of the transmission line. The contact mechanism is designed so it automatically adjusts to fit the diameter of the transmission line. The device further includes a grounding line coupled to the insert and, thus, the transmission line.